In order to be able to adjust the (peak-to-peak) stroke of a reciprocating motion or oscillating stroke motion of a welding wire, a device equipped with a carriage drive is known from the prior art, (EP1080818A2) in which it is possible to change the eccentricity of its eccentric. To this end, the eccentric rod must be manually changed from one bearing point on the eccentric to another bearing point on the eccentric. The ability to change positions of the bearing point on the eccentric disadvantageously requires a comparatively high design cost if the eccentric must be able to relay high speeds of the drive unit and as a result, comparatively powerful mechanical stresses act on the eccentric and the eccentric rod.